DNA repair

I have two questions to the NG:
1. Is the result of Bielas and Heddle, PNAS 97:11391-11396 (October 10
2000), namely that DNA replication is necessary for repair, a general
result, or does it (for some reason?) apply only to their transgenic
mouse cells? It seems like the latter, since otherwise our non
proliferating cells would be out of comission after some time shorter
than the average life span(?).
2. Are there any studies of how the nuclear genes coding for mtDNA
repair enzymes are themselves repaired? One can imagine a stable system
(biological or cybernetic) in which all repair mechanisms can also
repair each other (it's stable because it would take SIMULTANEOUS damage
to all repair mechanisms to destabilize it, which is unlikely), but if
the nodes of this system are not all connected to each other (i.e.
repairing each other) and there is an achiles heel node that is least
connected, the system would become unstable over time and might exhibit
some of the characteristics of ageing. Is pol gamma the only repair
enzyme for mtDNA? Does the nuc gene encoding it get repaired by anything
else?
-Iuval Clejan